Investigators participating in the CORE program for cancer-oriented research are examining the question of the cellular etiology of cancer. Specific aims of the program are concerned with elucidating: 1) What cellular "decisions" are entailed in the normal differentiative course of behavior contrasted with the neoplastic/malignant course? 2) What significant message or messages are imparted by oncogenic viruses to affect these decisions? 3) What biochemical mechanisms specifically control synthesis of proteins important to cell division, nucleic acid metabolism and immunological constitution? Specific projects supported by the grant include the study of: cell hybridization, cellular transformation with oncogenic viruses, fusion induction of mammalian eggs, protein initiation in a model mammalian cell-free system, control mechanisms of tumor virus expression in transformed cells, immunological interactions between host and tumor, study of SV40-Chinese hamster cell system, regulation of macromolecular synthesis in cell culture systems, histocompatibility antigens, regulatory processes in SV40-infected cells, macrophage growth factor, and electron microscopic studies of malignant tissues and cells.